TORONTO -- Mistie Delorey isn't sure where to turn next: the Fredericton mother has a dwindling supply of clobazam, a medication that prevents her eight-year-old son from experiencing life-threatening daily seizures -- and there's a critical shortage of the drug across the country.

"I'm terrified, I'm literally terrified," said Delorey, whose severely autistic and non-verbal son, Cameron, suffers from multiple types of seizures, including the potentially lethal kind.

"The fatal seizures will happen with anybody taken off this drug -- immediately. It's that serious. You can't be just taken off this drug for even one dose."

Clobazam, one of two anti-seizure drugs her son takes, has kept Cameron well-regulated over the last four years, dramatically reducing the frequency of episodes to about four a year from roughly 17 a day before he began taking the medication, she said.

But when Delorey went to refill his prescription more than two weeks ago, the pharmacy told her it had none in stock due to a Canada-wide shortage. Other Fredericton drugstores she contacted also couldn't accommodate her.

"Two of them outright said, 'We have some, but you're not getting it,' because they have patients who require that medicine and they're saving it for them, which I can understand."

A third said it would try to help her. But because the pills must be sent to a compounding pharmacy to be made into a liquid -- Cameron can only swallow pureed foods and liquids -- the drugstore wasn't able to fulfil her request.

She was finally able to secure four weeks' supply of the drug from the local hospital, but only with the help of the Canadian Epilepsy Alliance, a network of organizations that advocates for people with seizure disorders and their families.

"It was a huge relief that I secured a month's worth," said Delorey, whose supply of clobazam for Cameron is now down to about 2 1/2 weeks.

"And then slowly, hour by hour since that happened, I'm just: What do I do next month?"

Suzanne Nurse, chair of the Canadian Epilepsy Alliance Drug Shortage Committee, said an estimated 20,000 to 40,000 Canadians rely on clobazam to control their seizures and there have been three major shortages in the last three years.

Generic drug manufacturer Apotex provides 70 to 80 per cent of the clobazam sold in Canada, with the rest of the market covered by generic drug maker Teva Canada and Lundbeck Canada, which sells the drug under the brand name Frisium. Pro Doc Ltd. sells a private-label brand in Quebec.

Nurse said there was a disruption in the supply of clobazam made by Apotex last June, which was resolved a month later. But then the company posted a notice in early December that the medicine was again on back-order and the shortage wasn't expected to be resolved until this month.

"So there's been many months now where the main supplier of this drug has not been supplying the market," she said.

"We're in a situation where there's a very low supply or depletion of this drug in Canada, and it's going to take a period of time to get back to regular supply levels where people won't have any trouble getting the drug."

Nurse said she's been contacted by a number of patients or their families desperate for help to access clobazam, a benzodiazepine for which there is no suitable alternative for many patients.

A sudden discontinuation of clobazam is especially dangerous as it can cause life-threatening complications due to benzodiazepine withdrawal.

"They're terrified that their loved one is going to die as a result of not being able to obtain this medication ... I've spoken to people who have been seizure-free on this medication for decades. It's the only drug that's ever worked for some people," she explained.

A spokesman for Apotex said the company this week released a quantity of the medication, sold under the generic name Apo-Clobazam, to distributors, who will then ship the pills to pharmacies.

"We have also received a new consignment of raw material and have commenced manufacturing more tablets," Elie Betito said Wednesday. "Further product will be available to the market in early August."

Health Canada has been working with manufacturers, distributors, provinces and territories, and patient groups to come up with strategies to resolve the shortage of clobazam, which is considered a "medically necessary" product, said Ken Moore, acting director of health product compliance and risk management.

Moore said there can be multiple and complex factors behind drug-supply disruptions, including problems with global supply chains and accessing raw pharmaceutical ingredients.

"The work we're doing is trying to get a better ability to understand some of the factors at play and to be able to predict and preferably prevent shortages," he said, adding that Health Canada has been told by the drug maker that there should be enough product available "to meet the current need."

The Canadian Epilepsy Alliance said meeting that need is critical.

More than 300,000 Canadians are affected by epilepsy, a neurological disorder marked by sudden repeated episodes of sensory disturbance, loss of consciousness or convulsions related to abnormal electrical activity in the brain.

Not all seizures are classified as epileptic in nature. Seizures have a variety of causes, including Alzheimer's disease, a previous brain infection or injury, or the use of certain recreational drugs or medications.

Anti-convulsive medications are the main treatment for epilepsy and other seizure disorders, but many of these drugs -- not only clobazam -- have been or are currently in short supply.

"About 75 per cent of the drugs used to treat epilepsy in Canada had one or more shortages in the last five years," said Nurse, who works at Epilepsy Ontario.

"For people who live with epilepsy and their families, it's like an active fault line has developed under their feet and the drug supply has become extremely unreliable," she said.

"This is a crisis, and it needs to be treated as such."